1. Field of the Invention
The invention relates to a bearing arrangement for pump bearings in plastic housings such as in coolant pumps.
2. The Prior Art
Coolant pumps with plastic housings are known. In connection with this type of construction, the pump bearing is positioned in the injection molding die before the injection molding process is started, and integrated in the plastic housing in a safely secured position in the course of the injection molding process.
This method of securing the bearing has drawbacks in that during the injection molding process, the pump bearing is subjected to temperatures of up to 400xc2x0 C., which subjects the pump bearing to high thermal stresses. During the cooling process, the bearing sleeves are then radially distorted in the plastic material and often even deformed in this process. In the course of the subsequent manufacturing steps, the bearings then have to be greased and sealed.
In addition to the increased manufacturing and mounting expenditure connected therewith, the plastic coolant pumps with the pump bearing integrated therein in the injection molding process have the further drawback that the pump bearings must have a relatively high amount of clearance due to the technologically conditioned distortion of the outer ring in the plastic material. Such high play of the bearing necessarily results in severe xe2x80x9cknocking of the shaftxe2x80x9d. This makes it more difficult to seal the shaft with the shaft gasket and increases the mounting expenditure. Furthermore, this reduces the useful life of the bearing and, moreover, generates increased noise of the running pump.
Another drawback of coolant pumps with a bearing integrated in the plastic housing by injection molding consists in that these plastic housings cannot be tempered because of the pump bearing integrated therein, so that the plastic materials necessarily have a lower strength as compared to tempered plastics.
Furthermore, the recycling of plastic housings with pump bearings integrated therein by injection molding is very costly because the separation of the injected bearing from the plastic of the housing necessarily requires increased time and/or labor expenditure.
On the other hand, bearing arrangements in plastic housings of coolant pumps are known where the entire jacket surface of the pump bearing is glued into the associated plastic housing. The gluing gap between the plastic housing and the outer jacket of the bearing, which is required for transmitting the axial stresses of the bearing, requires manufacturing and mounting (or installation) tolerances that have a negative influence on the geometry of the sealing gap between the pump wheel and the associated boring of the housing, and thus on the leakage flow as an important factor influencing the degree of efficiency of the coolant pump. Thus, with justifiable manufacturing and/or mounting expenditure, coolant pumps with pump bearings glued into such pumps are either only capable of transmitting low axial stresses from the bearing to the pump housing, or the coolant pumps will then have a necessarily low degree of efficiency. Any optimization of such types of construction with glued-in pump bearings always require additional manufacturing and/or mounting expenditure, which is often very high.
It is therefore an object of the invention to develop a bearing arrangement for pump bearings in plastic housings, in particular for coolant pumps, that can be produced at favorable cost and manufactured and mounted in a simple manner, and which does not exhibit the aforementioned drawbacks afflicting the prior art, and which permits tempering of the plastic housing, which always ensures a high degree of efficiency of the pump combined with minimal manufacturing and mounting expenditure, which permits the use of bearings as pump bearings with low play of the bearing, and which offers all of the benefits resulting therefrom such as a prolonged service life, low development of noise, relief of the shaft sealing gasket, as well as many any benefits.
It is another object of the invention to provide a bearing arrangement that assures high transmission of axial force from the pump bearing to the pump housing combined with an optimal geometry of the sealing gap, and permits removal of the pump bearing without causing damage to the plastic housing, and, at the same time, clearly reduces the manufacturing and mounting expenditure as well as also the recycling cost.
These objects are achieved according to the invention by a bearing arrangement in particular for pump bearings mounted in or on coolant pump housings made of plastic, with an axial bearing support. A housing groove is arranged in the housing of the coolant pump and is provided with an inlet bore. A bearing groove, which, in the final mounted condition, is located opposite the housing groove, is provided on the bearing ring to be arranged in the seat of the bearing.
According to the invention, polyamide in the liquid state, for example, is filled via the inlet bore into the cavity formed by the groove of the housing and the groove of the bearing between the housing of the coolant pump and the bearing ring.
After the polyamide has cured, an injected plastic ring is formed in the cavity of the groove of the housing and the groove of the bearing. This plastic ring, which is connected with both the housing of the coolant pump and the bearing ring, permits a bearing arrangement for pump bearings that can be installed in the plastic housing of coolant pumps. Such a bearing system can be produced, installed and dismantled in a simple manner in terms of manufacturing technology and at favorable cost.
Due to the fact that the bearing is joined with the housing of the coolant pump only after the injection molding process has been carried out, it is also possible to distinctly improve the material properties of the plastic housing by tempering.
Since in connection with the dimensioning of the fit between the bearing and the seat of the bearing of the housing of the coolant pump, only pressed fits but no gluing gap measurements need to be taken into account, an optimal geometry of the sealing gap between the wheel of the pump and the bore of the housing can be ensured with only minimal manufacturing and mounting expenditure, and it is therefore possible to ensure a high degree of efficiency of the pump.
Because the bearings are neither injected nor clamped in any fixed manner, and any deformation of the outer bearing rings of the pump bearings is therefore avoided, it is possible to use such bearings as pump bearings with only minor play of the bearing, which results in obtaining all the benefits such as a relief of the shaft sealing gasket, which is connected with minor clearance of the bearing; a prolonged service life; low development of noise; and many others.
Because of the injected plastic ring that extends all around above the groove of the bearing and the housing of the coolant pump, and which is connected with both the bearing and the housing of the coolant pump, even high axial forces are transmitted without any problem from the pump bearing to the housing of the coolant pump.
Furthermore, by breaking the polyamide connection in a defined manner, the pump bearing can be removed without damaging the plastic housing, so that in addition to the expenditure for the manufacture and installation, the expenditure for recycling can be distinctly reduced as well.
Moreover, it is beneficial as well if the pump bearing and a shaft sealing gasket are jointly arranged in the bearing ring that is provided with a bearing groove.
In conjunction with the bearing that can be employed as defined by the invention with minor play (air) of the bearing, if the pump bearing and the shaft sealing gasket are arranged jointly, it is possible to exactly center the shaft, so that the installation of venting bores with the disadvantages resulting therefrom can be avoided.
Preferably, a running sleeve is arranged on the shaft in the area of the shaft sealing gasket in order to prevent the sealing lips of the shaft sealing gasket from becoming scored.
Either a sliding bearing or a roller (or antifriction) bearing is arranged in or on the bearing ring that is provided with a bearing groove.
It is characteristic, furthermore, that a belt pulley, which is connected to a plastic shaft, is connected with torsional strength with the outer ring of a pump bearing that is arranged on the bearing ring provided with a bearing groove. Such a pump bearing is arranged on the bearing seat, the sheet being provided with an inlet bore and a radial groove of the housing with the axial bearing support of the housing of the coolant pump, in such a manner that in the final mounted condition, the bearing groove is located opposite the housing groove, and the shaft sealing gasket is arranged directly below the pump bearing. A sleeve that is integrated on the impeller wheel is arranged on the free end of the plastic shaft. The sleeve runs in a sliding bearing that is made of plastic and arranged in the housing of the coolant pump.
This type of construction, in addition to the benefits gained according to the invention as explained above, also permits the use of a favorably priced, simple single-row grooved ball bearing with optimal running properties.
Preferably, bridges with grooves disposed between such bridges are arranged in the coolant pump housing on the periphery of the bearing seat, whereby the grooves are connected among each other by means of the housing groove that is provided with the inlet bore. These bridges simplify the manufacturing and mounting process required for joining the components due to the fact that because of the interrupted jacket surface of the bearing seat, pre-tensioning that is harmless to the bearing is made possible in the mounting process.
In the final mounted condition, after the polyamide has hardened, the grooves between the bridges increase the force- and form-locked xe2x80x9cjointed assemblyxe2x80x9d because the surface area has been distinctly increased, and, furthermore, increase the axial force that can be transmitted between the housing and the bearing.
In that connection, the open xe2x80x9ctie-upxe2x80x9d of the grooves to the environment of the coolant pump housing ensures optimal venting (or bleeding) of all grooves and flutes between the housing and the bearing as the polyamide is being filled in, which leads to optimal anchoring of the bearing in the plastic housing.
The bridges with the grooves arranged therebetween can be arranged in the axial direction in a straight line, and/or slanted in relation to the axial direction, and/or curved relative to the axial direction. The shape of the bridges and the grooves arranged therebetween serves the play-free centering of the bearing and simplifies the manufacturing process due to optimal removal of the mold in the injection molding step, and, furthermore, permits increasing the maximal axial force than can be transmitted between the bearing and the housing.